The present invention relates generally to storage battery ventilation, and more particularly, to an improved vent cap for use in connection with motive power storage battery designs.
As a result of various chemical processes which occur when storage batteries are in use, as well as during the charging of such storage batteries, gases such as hydrogen and oxygen are often produced. Such gases are generally vented to the atmosphere in order to relieve the battery of internal pressures which could otherwise result. In performing such ventilation, the following two factors should be considered.
First, since the gases being vented are hydrogen and oxygen, care must be taken to reduce the possibility of igniting such gases. This is particularly important during battery charging, since gassing often becomes more prevalent during such periods, and since electrical connections made to the terminals of the battery can create a potential for sparks. Under such conditions battery damage can result from sparks or ignited gases reentering the battery.
Secondly, care must be taken to reduce the loss of battery electroyte through the vent, either as a result of misting which occurs in connection with battery gassing, or as a result of battery movement. Those skilled in the art recongnize that use of venting means for preservcation of electrolyte reduces the need for additional servicing procedures and often prevents electrolyte loss which may compromise the service life of the battery. However, battery electrolyte levels must still be carefully monitored and replenished, as needed.
A variety of devices have been developed in an attempt to accommodate the foregoing by providing a vent cap which proves both safer and more reliable in operation, yet lends itself to manufacture. In an effort to inhibit sparks and ignited gases from reentering the battery, some vent caps are provided with proportioned apertures or slits which are sufficiently large to enable ventilation of gases from the battery, yet which are sufficiently small to retard the passage of sparks or ignited gases. Other vent caps have been designed which incorporate a permeable venting frit through which gas may exit, but which serves as a physical barrier to sparks and ignited gases outside the vent cap.
To reduce the loss of electrolyte, vent caps are generally provided with baffles or passageways which develop relatively contorted flow paths designed to condense and facilitate the return of electrolyte collected within the vent cap to the cell of the battery with which the vent cap is associated. The design of the flow paths is central to the effectiveness of the vent cap in reducing electrolyte loss.
U.S. Pat. No. 4,517,262, issued, May 14, 1985, to Beidler and commonly assigned, discloses a vent for a storage battery which significantly contributes to the solutions of the problems outlined above.
The present invention provides improved solutions by employing a novel venting path system which enhances electrolyte retention when electrolyte pumping occurs in battery use, and concurrently offers manufacturing feasibility through simplicity of production and assembly. The present invention also teaches an improved venting system, particularly applicable for commonly venting a plurality of battery cells, which inhibits the loss of battery acid from one cell to another commonly vented cell.